The invention relates to a pump for discharging doses of liquid, gel-like or viscous substances from a container according to the preamble of claim 1 and to a dispenser with such a pump.
In the field of cosmetics, pumps are often used for discharging lotions, creams, shampoos, toothpaste, perfumes, aftershaves, etc. These are generally piston pumps. Positive-displacement pumps are also used for toothpaste. Compared to piston pumps, positive-displacement pumps have the advantage of containing far fewer components and being less sensitive to abrasion.
The pump body which bounds a displacement space has a shape which, following compression, returns to the starting position on account of its own spring force restoring elasticity and, by means of the vacuum generated during the process, sucks up the substance contained in a container. Known pump bodies are configured as elastic balls, dome-like bodies or folding bellows.
A dispenser for free-flowing media is known from DE 81 38 264 U1 and has an elastically restoring squeezing head which is arranged on a dispenser housing and has a valve nozzle opening and in whose bottom there is provided an inlet valve at which an intake hose ends. The valve nozzle opening of the squeezing head consists of lips which move tightly together and close the nozzle opening. The squeezing head itself has a bellows-like structure. Reliable closing of the valve nozzle opening requires permanent restorability of the material used.
However, it has proved to be a disadvantage that the materials available for these types of pump bodies of positive-displacement pumps generally only provide limited restorability because they either undergo fatigue after multiple actuation, or because the elasticity is not sufficient to generate a large enough vacuum. Positive-displacement pumps are furthermore not self-priming, unless additional springs are used for the outlet valve and the inlet valve which may be present. The advantage of positive-displacement pumps specifically containing few components is thus lost.
A filled toothbrush is known from DE 36 03 475 C1, in whose toothbrush handle there is a space for a tooth-cleaning agent, and whose toothbrush head has a duct which leads from the space to an outlet opening in the region of the toothbrush bristles. Provided at the other end of the toothbrush handle is an actuating member for actuating a pumping device which is arranged between the space and the duct and has a valve whose closing direction faces the supply space. This pumping device is configured as a piston pump which delivers tooth-cleaning agent into the duct by means of a piston rod. Piston pumps of this type are susceptible to wear and require many components.
The object of the invention is therefore to provide a pump for the metered discharge of liquid, gel-like or viscous substances from a container, which pump is of simple construction and, at the same time, is self-priming.
As a result, a positive-displacement pump is provided, which is not only very inexpensive on account of the design of the outlet valve and its integral configuration on the pump body, but also operates reliably and in a self-priming manner.
The problem of self-priming is primarily a problem with the outlet valve, since it must be assured that, when the vacuum is built up, no air is sucked in via the outlet valve. In providing such assurance, it is preferable, of course, to save the cost of a spring-loaded valve.
By virtue of the fact that the outlet valve has successfully been incorporated integrally into the pump body, the outlet valve here not only closes tightly, but the pump is also self-priming because the valve plate, which is convex in the delivery direction, that is to say curved outward, with an incision forming the valve outlet in the form of a lip seal opens easily in the delivery direction, i.e. outward, but closes all the more tightly, the greater the pressure exerted in the opposite direction. Thus, when the compressed pump body builds up a vacuum, the suction arising on the valve plate will squeeze together the incision and thus the lip seal to be completely airtight. The substance contained in a container, i.e. the product mass, can be sucked out of the container. If, in contrast, the pump body is squeezed together, the substance sucked into a displacement space of the pump body can be discharged through the automatically opening incision. The small outward curvature causes a tendency of the outlet valve to open under increased pressure in the displacement space.
The closing function of the outlet valve is so reliable that an air vacuum remains fully intact even over several days. The valve seats otherwise required for an outlet valve are dispensed with completely. The outlet valve suffers fatigue far less readily than conventional valves and is therefore long-lasting.
In the case of toothpaste, cosmetic lotions, shampoos, conditioners and body creams of high viscosities, tests involving such pumps resulted in excellent suction and discharge performances. Liquid media, alcoholic liquids and aftershaves worked quite exceptionally well in conjunction with a standpipe which protrudes into a container.
The incision in the valve plate is preferably arranged centrally so that the closing forces act on the lip seal as evenly as possible.
The size of the valve plate is preferably adapted to the length of the lip seal, so that the incision then extends essentially over the width of the valve plate.
The pump body preferably comprises a pump outlet which is in the shape of a neck or stack and has the outlet valve at its free end, a sealing guide being provided for arrangement in a delivery duct of a dispenser head which can be fitted on top. The design of the valve plate as claimed in claim 6 is preferred, since this increases the speed of response and thus reduces the sluggishness as much as possible.
The shapes of the pump bodies ensure a high level of shape-related spring force restoring elasticity. A force of curvature present here results in the fact that a compressed pump body becomes erect again spontaneously when the pressure is relieved.
In the case of a pump body configured in a hood- or dome-like manner, said pump body may have uneven wall thicknesses, as explained in claim 9. If the upper part of the hood or dome has a less thick wall than the central and lower part, this results in the fact that the initial delivery is dispensed with less pressure being expended than for the delivery from the central and lower displacement space. For this purpose, the greater wall thickness in the central and lower part ensures that, when the central and lower displacement spaces are emptied, the strong restoring force prevailing therexe2x80x94on account of the greater wall thicknessxe2x80x94allows the pump body to shoot back into the starting position spontaneously and carries the weaker upper part along with it. Weaker elasticity of an upper part of the pump body can thus be desirable in order to reduce the pressure necessary at the beginning to actuate the dispenser.
Preferred materials for the pump body and thus including the outlet valve are mentioned herein. It is possible to use silicone rubber here, which is advantageous because this material, in contrast to thermoplastics, is aromatight and, since it is heat-resistant, can also be sterilized.
The pump body may be provided with an inlet valve, as is customary in conjunction with airless and standpipe dispensers. Butterfly valves have the advantage of closing automatically and without spring loading. A particularly preferred inlet valve is mentioned which can be produced far more inexpensively since it has only one part and thus no costs for assembly.
The pump body furthermore provides the advantage that its dimensions can be selected as a function of the required delivery volume in one dispensing stroke. Metered discharge of specific substance volumes is thus possible in a simple manner. Preferred discharging volumes are within a range of between 10 mcl and 1000 mcl.
The squeezing-together of the pump body in a discharge device, in particular a dispenser, is preferably effected by means of an actuating element which imposes a circumferentially distributed pressure centrally on the pump body. Whenever the pump body is of hood or dome-shaped configuration and has an outlet projection in the shape of a neck or stack, exerting the pressure centrally on the outlet projection in the shape of a neck or stack should be avoided. In the case of spot-like central exertion of pressure, such a pump body tends to simply invert inward, which means that the pump body is only partly emptied. The spring restoring force from this inversion state is only slight.
A pressure distribution plate provides assurance that the pressure is exerted uniformly on the entire upper outer surface of the pump body without loading the pump body and possibly the stack-like projection protruding out of the hood or dome. The pump body can thus be squeezed together to form a flat disk. An extremely inexpensive and practical solution, in this case, is provided by integrating this pressure distribution plate in an actuating knob as a cross-shaped pressure element.
The surprising result was that exerting such a pressure over the entire area develops an exceptionally strong restoring force, even in pump bodies made of very soft materials. Consequently, even highly viscous media can be delivered reliably with the slightest finger pressure, if the dispenser operates as an airless system with a follow-on plunger. When using standpipes, consideration must be given to the fact that, in the case of viscous media, there are additionally friction forces in a standpipe which bind strong delivery forces. Consequently, in conjunction with standpipes and media of higher viscosity, the pump body should have a high restoring force based on the shape and material.
The dispenser and thus the actuating element acting on the pump body can be actuated by finger pressure by means of an actuating knob or by means of a dispenser head which can be displaced axially in relation to the pump body.
The pump may be installed in any desired discharge devices. An area of application includes dispensers for substances of the cosmetics industry mentioned at the beginning. The pump can also be incorporated in a manual or electric toothbrush.
Further configurations of the invention emerge from the following description and the subclaims.